Polarizer for use in antenna and transmission line systems



R. A. MOORE 3,216,017 POLARIZER FOR USE IN ANTENNA AND TRANSMISSION LINESYSTEMS Nov. 2, 1965 2 Sheets-Sheet 1 lsu" IIAI Y Filed DeG. 4, 1962 1NVEN TOR.

v @Fx R. A. MOORE 3,216,017

POLARIZER FOR USE IN ANTENNA AND TRANSMISSION LINE SYSTEMS Nov. 2, 19652 Sheets-Sheet 2 Filed D60. 4, 1962illulllllllllllllllmlllnmmnmwilliiilllllllllllllllli"iwniiilllillllllliiiliiw!INVENTOR.

ROBERT A. MOORE United States Patent Office 3,216,017 Patented Nov. 2,1965 3,216,017 POLARIZER FOR USE IN ANTENNA AND TRANSMISSION LINESYSTEMS Robert Allen Moore, Orange County, Fla., assignor toMartin-Marietta Corporation, Middle River, Md., a corporation ofMaryland Filed Dec. 4, 1962, Ser. No. 242,256

11 Claims. (Cl. 343-756) This invention relates to a polarizing devicefor transforming linearly polarized energy to elliptically polarizedenergy and more particularly to a polarizing device having a rotatablymounted, axially adjustable wedge shaped dielectric polarizer so thatwhen the dielectric polarizer is rotated from a neutral position, avariable degree and sense of elliptical polarization of the energy isobtainable, and when the dielectric polarizer is moved axially theimpedance of the polarizing device is varied.

During the extensive development of the electronic arts in the past twodecades, a need arose for a device capable of transforming and handlingelliptically polarized energy particularly in electronic apparatusoperating in the microwave range. Many techniques have been employed butcompletely satisfactory conversion of linearly polarized energy toeliptically polarized energy has not been heretofore achieved withoutthe use of highly complicated, bulky and expensive mechanization.Whenever a simplified and inexpensive technique was exploited by antennadesigners, serious manufacturing problems attached in the form of closetolerances and precision location and size of components. Accordingly,scientists skilled in the antenna art have long searched for a microwavepolarizing device capable of eliiciently and effectively convertinglinearly polarized energy to elliptically polarized energy. Desirably,such polarizing devices should have low tolerance and size requirements,high peak power handling capability in the order of 90% or better,semi-automatic adjustability for variably converting linearly polarizedenergy to right or left hand elliptically polarized energy, and simpleand expedient means for varying the impedance of the device.

For purposes of clarity and understanding of the present invention, thefollowing definitions of several terms hereinafter referred to arehereby incorporated:

Linear polarization-An electromagnetic wave is linearly polarized whenthe electric field continuously remains parallel to a fixed line whichis perpendicular to the direction of propagation.

Elliptical polarization-A plane electromagnetic wave, at a givenfrequency, is elliptically polarized when the extremity of the electricvector describes an ellipse in a plane perpendicular to the direction ofpropagation.

Circular plarizafi0n.-A special case of elliptical polarization whereinthe extremities of the electric vector describes a circle in a planeperpendicular to the direction of propagation.

Left-hand circular polarization-When the direction of rotation of acircular or elliptical polarized wave is such as to be acounterclockwise wave receding from an observer.

Right-hand circular p0larization.-When the direction of rotation of acircular or elliptical polarized wave is such as to be a clockwise wavereceding from an observer.

Dominant mode.-The mode of energy at the lowest cutoff frequency.

TEN, moda-The dominant mode of energy in a rectangular waveguide.

TEU moda-The dominant lmode of energy in a circular waveguide.

Polarizer.-A device which takes a source of one form of polarized energyand transforms it into a source of another form of polarized energy.

Dielectric- A non-conducting material, having low energy losses in themicrowave range.

Dielectric constant.-A measure of the ability of a dielectric materialto store electrical potential energy under the influence of an electricfield; measured by the ratio of the capacitance of a condenser with thematerial as the dielectric to its capacitance with a vacuum as thedielectric.

Peak-power handling capability.-The maximum power a waveguide can carrywithout breakdown. Breakdown being defined as the point at which theelectric field produces an arc discharge.

A few of the prior known techniques for converting linearly polarizedenergy to elliptically polarized energy are as follows:

One well known technique is the Orthogonal Probe Technique whichutilizes probes positioned in a circular waveguide to shift the phaseangle of the dominant mode TEH wave energy propagating down the circularwaveguide. This technique includes rod-like members positioned at a 45angle to the electric field vectors of the linearly polarized energypropagating down a circular waveguide. Generally, this method uses atleast two rod-like probes approximately Vs of a Wavelength apart toconvert a dominant mode TEM linearly polarized wave to a dominant modeTEn circularly polarized wave. The sense of polarization, i.e.,right-hand or left-hand circular polarization, depends upon whether theprobes are offset 45 to the right or left of the direction of theelectric field vectors of the linearly polarized energy. The OrthogonalProve Technique is unsatisfactory in many respects. By Way of example,very close tolerances are required in properly positioning the probesboth with respect to the circular waveguide and with respect to eachother; semi-automatic adjustability for converting linearly polarizedenergy to left-hand or right-hand circularly polarized energy is notpossible since precise positioning of the probes is a mandatoryrequirement necessitating absolute and rigid fabrication duringmanufacturing; simple and expedient means for varying the impedance ofthe Orthogonal Probe device is not obtainable without bulky, complex andexpensive mechanization; and high peak power handling capabilities inthe order of or better has not been possible.

Another well known technique is the Dielectric Slab Polarizer Techniquewhich utilizes a fiat slab of dielectric material specially shaped andprecisely positioned within a circular waveguide. The dielectric slabused in this technique is conventionally referred to as a quarter-waveplate and is approximately three wavelengths long at the centerfrequency of the linearly polarized energy. The end portions of thequarter-wave plate may assume several configurations to form aquarter-wave matching portion. That is to say, a rectangular, triangularor other geometrically shaped wedge portion of one quarter wavelengthlong may be removed from the ends of the quarterwave plate so as toprovide a quarter-wave matching portion. The quarter-wave plate isconventionally positioned at an angle of 45 to the right or left of thedirection of the electric field vectors of the linearly polarized energypropagating down the waveguide so as to produce a dominant mode TEMcircularly polarized Wave from a dominant mode TEH linearly polarizedWave. The sense of polarization, i.e., right-hand or left-hand circularpolarization, depends upon whether the quarter-wave plate is olset 45 tothe right or left of the direction of the electric field vectors of thelinearly polarized energy. Though the Dielectric Slab PolarizerTechnique is satisfactory in many respects, it contains several inherentdisadvantages some of which are close tolerance requirements withrespect to the precise formation of the quarter-wave matching portions;semi-automatic adjustability not easily obtainable since thequarter-wave plate must be precisely located both angularly and axiallyand requires absolute and rigid fabrication during manufacturing; simpleand expedient means for varying the impedance of the device notobtainable without bulky, complicated and expensive mechanization; andhigh peak power in the order of 90% or better not achievable.

Another well known technique is the Eccentric Circular WaveguideTechnique which employs a distorted section of the circular waveguide toconvert a dominant mode TEM linearly polarized wave to a dominant modeTEM elliptically polarized wave. The distorted section of the circularwaveguide is elliptically shaped and is three to four wavelengths longat the center frequency of the linearly polarized energy. Theyconversion of linearly polarized energy to elliptically polarizedenergy is perfected as a direct result of distorting the mode orelectric -field shape of the linearly polarized energy propagating downthe circular wavegui-de. This latter technique also involves severalinherent disadvantages some of which are the close tolerancerequirements with respect to the precise formation of the ellipticallyshaped distortion; the lack of semi-automatic adju-stability of thesense of elliptical polarization; and the absence of simple means forvarying the impedance of the device.

In accordance with the present invention, a simple and ellicientpolarizing device is provided for transforming dominant mode TENlinearly polarized energy to dominant mode TEH elliptically polarizedenergy by employing an elongated dielectric polarizer having a wedgeshaped portion which polarizer is adjust-ably mounted within .a circularwaveguide and extends at least partially into a transition waveguidesection. The transition waveguide connects the circular waveguide to arect-angular waveguide. The dielectric polarizer is rotatable within thecircular waveguide `and when in a neutral position, no transformation ofthe linearly polar-ized wave to a circularly polarized wave occurs butwhen rotated clockwise or counterclockwise from the neutral position,the linearly polarized energy propagating along the rectangularwaveguide is converted to elliptically polarized energy in one directionor the other, respectively. It should be noted that the rotatablefeature of the dielectric polarizer advantageously providessemi-automatic adjustability of the degree and sense of ellipticalpolarization of the propagating energy. In addition to the rotatableadjustment, the dielectric member is axially adjustable with respect tothe circular waveguide for varying the irnpedance of the polarizingdevice.

It is, accordingly, a primary object of the present invention to providea polarizing device for transforming dorninant TEU, mode linearlypolarized energy to dominant TEM elliptically polarized energy.

It is another object of the present invention to provide a polarizingdevice which is semi-automatically adjustable for varying the degree andsense of elliptical polarization of the propagating energy.

It is another object of the present invention to provide a polarizingdevice which has simple and expedient adjustable means for varying theimpedance of the device.

It is another object of the present invention to provide a polarizingdevice which employs a wedge shaped dielectric polarizer fortransforming dominant mode TEM linearly polarized energy to dominantmode T E11 elliptically polarized energy.

It is another object of the present invention to provide a polarizingdevice which employs a wedge shaped, rotatably and axially adjustable,dielectric polarizer for transforming dominant mode TEH linearlypolarized energy to dominant mode IT1311 elliptically polarized energywherein rotation of the dielectric polarizer causes the degree and senseof elliptical polarization to be varied, and axial movement of thedielectric pol-arizer causes the impedance of the polarizer to bevaried.

These and further objects and advantages will become more apparent uponreference to the following description and claims and the appendeddrawings wherein:

FIGURE 1 is -an isometric view of a polarizing device in accordance withthe present invention which is adapted for specific use as an antenna.

FIGURE 2 is a cross-sectional view of the polarizing device taken alongthe plane 2 2 of FIGURE ll;

FIGURE 3 is a cross-sectional view of the polarizing device taken `alongthe plane 3 3 of FIGURE l;

FIGURE 4 is an end View of the polarizing device taken along the plane 44 of FIGURE 1;

FIGURE 5 is an end view of the polarizing device taken along the plane 55 of FIGURE l;

FIGURE 6 is an isometric view of a polarizing device in accordance withthe present invention which is adapted for specitic use as atransmission line;

FIGURE 7 is a cross-sectional view of the polarizing device taken Aalongthe plane 7 7 `of FIGURE 6;

FIGURE 8 is a cross-sectional view of the polarizing device taken alongthe plane 8 8 of FIGURE 6;

FIGURE 9 is an end view of the polarizing device taken along the plane'9 9 of FIGURE 6; and

'FIGURE 10 is lan end view of the polarizing device taken along theplane 10-10 of FIGURE 6.

Detailed description of FIGURES 1-5 Referring now in detail to FIGURE 1,there is shown an isometric view of a preferred embodiment of thepolarizing device which is adapted for specific use as an antenna.- Thewedge shaped dielectric polarizer, generally indicated at 10, is mountedin a circular waveguide, generally indicated at 12, and extends at leastpartially into a transition waveguide section, generally indicated aty14. Transition section 14 connects a rectangular waveguide, generallyindicated at 16, to the circular waveguide 12. Polarizer 10 isadjustably held in position within the circular waveguide 12 by the setscrews *18.

It will be apparent that other well known means for adjustably holdingpolarizer 10 in position may be substituted for the set screws .18without departing from the spirit and scope of the present invention.Although four set screws apart are shown, it is to be understood thatmerely one set screw may suflice so -long as it frictionally holds thepolarizer 10 in position within the circular waveguide 12.

Referring now in detail to FIGURES 2-5 there are shown cross-sectionaland end views of the polarizer device taken along the planes 2 2, 3 3, 44 and 5 5, respectively, of FIGURE l.

The polarizer 10 compri-ses a wedge-shaped body portion 20 connected toa cylindrical neck portion 22 which is connected to a cylindrical headportion 24. A conical dielectric rod antenna 26 is connected to the head24 on the side thereof remote from the neck portion 22. Rod -antenna 26may `be blunt ended, as shown, or pointed depending upon the necessaryand desired radiation pattern. The body portion 20 of polarizer 10 has awedge Shaped end 2S which appears similar in many respects to thewedge-'shaped shank portion of a conventional screwdriver. Set screws 18frictionally hold polarizer 10 in a desired position within the circularwaveguide 12. Wedge-shaped end 28 of polarizer 10 extends at leastpartially into the transition waveguide section 14 which has one endintegrally connected to circular waveguide 12 and the other endintegrally connected to rectangular waveguide 16. The open end of thecircular waveguide 12 has a peripheral U-shaped flange 29 which servesas a quarter wave choke for reducing side lobes of the radiationpattern. The inside diameter of the circular waveguide 12 is slightlylarger than the diameter of the neck 22 of polarizer 10 and slightlysmaller than the diameter of the head 24 of polarizer l10 so thatpolarizer 10 can be -slidably inserted into circular waveguide 12 untilthe peripheral surface 32 of head 24 abuts the edge 34 of circularwaveguide 12 and frictionally hel-d in ra desired angular and axialposition by set screws 18.

Mode of operation of FIGURES 1-5 A detailed mode of operation of thepolarizer device of FIGURES l-5 is as follows:

With the polarizer in the position shown, i.e., the sharp edge of thewedge 28 parallel to the long side of the rectangular waveguide 16, anydominant mode TEN, linearly polarized energy propagating down therectangular waveguide 16 toward the circular waveguide 12 will not betransformed or converted into dominant mode TEM elliptically polarizedenergy. This is so because the sharp edge of the wedge 28 of polarizer10 is perpendicular to the electric vector of the dominant mode TEMlinearly polarized energy propagating down the rectangular waveguide 16.The wedge 28 of polarizer 10 in this case produces no phase shift of theelectric field, but produces only a transformation from the dominantmode TEN, linearly polarized energy in the rectangular waveguide 16 tothe dominant mode TEu linearly polarized energy in the circularwaveguide 12. This transformation from TEN mode to TEu mode is caused bythe gradual transition of the waveguide system from the rectangular tothe circular. It is well known by antenna experts that the dominant modein a rectangular waveguide is the TEM, mode and the dominant mode in acircular waveguide is the TEn mode. Accordingly, a detailed technicalexplanation of this transition is not considered necessary for purposesof describing the present invention.

To achieve the desired degree and sense of transformation, one or moreof the set screws 18 are loosened and polarizer 10 rotated clockwise orcounterclockwise up to 90 displaced from the position shown. With thepolarizer in its new position, any dominant mode TEN linearly polarizedenergy propagating down the rectangular waveguide 16 toward the circularwaveguide 12 will be transformed into dominant mode TE11 ellipticallypolarized energy. This is so because the sharp edge of the wedge 28 ofpolarizer 10 is no longer perpendicular to the electric vector of thedominant mode TEM, energy propagating down the rectangular waveguide 16.The polarizer 10 due to its shape and the difference in dielectric mediabetween the polarizer 10 and the air lled rectangular waveguide 16,produces a shift in phase of the electric vector of the dominant modeTEM linearly polarized energy propagating toward the circular waveguide12. In time quadrature this phase shift produces a rotation of theelectric vector. This rotation is such that the extremities of theelectric vector describe an ellipse. The

sense of rotation, either clockwise or counterclockwise, and the degreeof ellipticity being determined by the angular displacement of thedielectric polarizer 10 from its neutral position.

Before the loosened set screws 18 are tightened, the polarizer 10 may beaxially moved for impedance matching purposes. This is possible becausethe polarizer 10 constitutes an obstruction in the path of thepropagating energy. A portion of this propagating energy strikes thepolarizer 10 and is reflected back in a reverse direction. This iscalled reflected energy. The ratio of the propagating energy to thereflected energy constitutes the impedance transformation of the device.An ideal condition occurs when there is no reflected energy. Thus, anyaxial movement of the polarizer 10 will produce a change in the amountof reflected energy, thereby producing a change in impedance of thepolarizing device.

After the polarizer is axially adjusted and the desired impedanceattained, the loosened set screws 18 are tightened. The polarizer deviceis now adjusted for both receiving and transmitting of dominant mode TEHelliptically polarized energy and more desirably adapted for receivingand transmitting dominant mode TEM elliptically polarized energy in themicrowave range.

For exemplary purposes only, the following dimensions andcharacteristics of the polarizer device depicted in FIG- URES 1-5 werefound highly satisfactory. It should be noted that the wavelengthsreferred to in the dimensions and characteristics below listed are freespace wavelengths.

Dimensions Transition Length- 2 wavelengths long at center frequency ofoperation. Circular Waveguide Diameterwhere dlzPhysical diameter ofcircular waveguide when dielectric polarizer is in position;

dzDiameter of a circular waveguide which would propagate the dominantmode TEM elliptically polarized energy when the dielectric polarizer isnot in position; and

KzDielectric constant of the dielectric polarizer.

Length of Taperll/z wavelengths long at center frequency of operation.

Characteristics Dielectric Constant-2 to 3.

Dissipation Factor-0.0003.

Efllciency (based on directive gan)-75%.

Axial ratio at design frequency-0.5 db.

Percent bandwidth for 3 db ellipticity-20%.

Percent bandwidth for 1.5 VSWR-30%.

Power handling in percent of rated rectangular waveguide- 3 db beamwidth(practical limits)-20 to 70.

Maximum side lobes-minus 20 db.

Front-tO-back ratio (40 cone)minus 30 db.

It is to be understood that the polarizer device depicted in FIGURES l-Smay also receive dominant mode TE elliptically polarized energy. In thiscase, the polarizer 10 transforms the dominant mode TEM ellipticallypolarized energy to the dominant mode TEM linearly polarized energywhich then propagates down the transition waveguide section 14 whereinit is transformed to the dominant mode TEN linearly polarized energywhich in turn propagates down the rectangular waveguide 16 away from thecircular waveguide 12.

A polarizing device constructed in accordance with the foregoingdimensions will also transform dominant mode TEM linearly polarizedenergy to dominant mode TEM circularly polarized energy when thepolarizer is rotated approximately 40 clockwise or counterclockwise fromthe position depicted in FIGURES 1-5 (neutral position), which isapproximately such that the sharp edge of the wedge 28 of polarizer 10is parallel to the long sides of the rectangular waveguide 16.Accordingly, the transformation of the energy will be from TEm modelinear to TEU mode elliptical polarization whenever the polarizer 10 isrotated any amount less than or more than approximately 40 from itsneutral position.

Detailed description of FIGURES 6-10 Referring in detail to FIGURE 6,there is shown an isometric view of an alternate embodiment of thepolarizing device which is adapted for specific use as a transmissionline. The wedge-shaped dielectric polarizer, generally indicated at 40,is mounted in a circular waveguide, generally indicated at 42, andextends at least partially into a transition waveguide section,generally indicated at 44. Transition section 44 connects a rectangularwaveguide, generally indicated at 46, to the circular waveguide 42.Polarizer 40 is adjustably held in position within the circularwaveguide 42 by the set screws 48.

It will again be apparent that other well known means for adjustablyholding polarizer 40 in position may be substituted for the set screws48 without departing from the spirit and scope of the present invention.Although four set screws 90 apart are shown, it is to be againunderstood that merely one set screw may sutiice so long as itfrictionally holds the polarizer 40 in position within the circularwaveguide 42.

Referring now in detail to FIGURES 7-10, there are shown cross-sectionaland end views of the polarizing device taken along the planes 7-7, 8 8,9 9 and 10-10, respectively, of FIGURE 6.

The polarizer 40 comprises a wedge-shaped body portion 50 connected to acylindrical neck portion 52 which is connected to a conical head portion54. Conical head portion 54 is pointed, as shown at 56, for impedancematching purposes. The body portion 50 of polarizer 40 has a wedgeshaped end 58 which appears similar in many respects to the wedge-shapedshank portion of a conventional screwdriver. Set screws 48 frictionallyhold polarizer 40 in a desired position within the circular waveguide42. Wedge-shaped end 58 of polarizer 40 extends into the transitionwaveguide section 44 which has one end integrally connected to circularwaveguide 42 and the other end integrally connected to rectangularwaveguide 46. The inside diameter of the circular waveguide 42 isslightly larger than the diameter of the neck portion 52 of polarizer 40so that polarizer 40 can be slidably inserted into the circularwaveguide 42 and frictionally held in a desired angular and axialposition by set screws 48.

The mode of operation of the embodiment of FIG- URES 6-10 issubstantially the Same as that above set forth in detail with respect tothe embodiment of FIG- URES 1-5. The primary difference being that thetransformed dominant mode TEM elliptically polarized energy continues topropagate down the circular waveguide 42 away from the rectangularwaveguide 46 rather than being radiated into the atmosphere, as in thecase of the polarizer device depicted in FIGURES 1-5. Also, thedimensions and characteristics of the polarizer of FIG- URES 6-10 issubstantially the same as the polarizer of FIGURES 1-5. In addition, ithas also been found that the transformation of energy from linear tocircular polarization takes place when the polarizer 40 is rotated 40from its neutral position (position shown in FIG- URES 6-10).

It will be apparent from the foregoing that the present inventionprovides a unique technique for converting dominant mode TEN linearlypolarized energy to dominant mode TEM elliptically polarized energywithout the use of highly complicated, bulky and expensivemechanization. The use of a wedge-shaped dielectric polarizer angularlyand axially adjustable within a circular waveguide in combination with agradually tapered transition waveguide for coupling a rectangularwaveguide to the circular waveguide, uniquely overcomes the inherentdisadvantages of prior known polarizing devices.

The rotatable feature of the present polarizer effectively andefficiently provides semi-automatic adjustability of the degree andsense of elliptical polarization of the propagating energy. In addition,the axial adjusting feature of the present invention accurately providesexpedient means for va-rying the impedance of the polarizing device.

It will also be apparent that the polarizing devices of the presentinvention are simple in construction, economical to manufacture andhighly reliable in achieving the desired objects and performing theintended functions.

While several embodiments of the present invention have been describedin detail, it is to be understood that other modifications arecontemplated which would be yapparent to persons skilled in the artwithout departing from the spirit of the invention or the scope of theappended claims.

I claim:

1. A polarizing device comprising, in combination:

(a) a rectangular waveguide;

(b) a circular waveguide;

(c) a tapered waveguide transition section coupling one end of saidrectangular waveguide to one end of said circular waveguide;

(d) elongated dielectric mean-s positioned within said circularwaveguide and extending into said transition section; and

(e) means for adjustably holding -said dielectric means within saidcircular waveguide so as to provide both angular and axial adjustment ofsaid dielectric means with respect to said circular waveguide;

(f) said circular waveguide having a diameter wherein said circularwaveguide will not propagate wave energy when said dielectric means isnot in position within said circular waveguide so that,

where d1 equals the physical diameter of said circular waveguide whensaid dielectric means is in position, d equals the diameter of acircular waveguide which would propagate the dominant mode TEu of saidenergy when said dielectric means is not in position, and K equals thedielectric constant of said dielectric means;

(g) said dielectric means being rotatable to a first position whichcauses dominant mode TEM, linearly polarized energy to be propagated insaid circular waveguide, being rotatable to a second position whichcauses dominant mode TEU, left-hand, circularly polarized energy to bepropagated in said circular waveguide, and being rotatable to a thirdposition which causes dominant mode TEM, righthand, circularly polarizedenergy to be propagated in said circular waveguide;

(h) said dielectric means being rotatable to any position other thansaid first, second and third positions, to achieve a variable degree andsense of transformation of said dominant mode TEM linearly polarizedenergy to dominant mode TEM elliptically polarized energy; and

(i) said ydielectric means is axially adjustable with respect to saidcircular waveguide for varying the impedance of said device.

2. A polarizing device in accordance with claim 1 wherein the length ofsaid transition section is approximately two wave lengths long in freespace at the center frequency of said energy.

3. A polarizing device in accordance with claim 2 wherein the length ofsaid body portion of said dielectric means is approximately one andone-half wavelengths long in free space at the center frequency of saidenergy.

4. A polarizing device in accordance with claim 3 wherein the physicaldiameter of said circular waveguide is approximately one-half wavelengthlong in free space at the center frequency of said energy.

5. A polarizing device comprising, in combination:

(a) a rectangular waveguide;

(b) a circular waveguide;

(c) a tapered waveguide transition section coupling one end of saidrectangular waveguide to one end of said circular waveguide, saidtransition section being approximately two wave lengths long in freespace at the center frequency of said energy;

(d) elongated dielectric means positioned within said circular waveguideand extending into said transition section; and

(e) means for adjustably holding said dielectric means within saidcircular waveguide;

(f) said dielectric means comprising a wedge-shaped body portionconnected to a cylindrical head portion, said body portion beingapproximately one-half wavelength long in free space at the centerfrequency of said energy and said head portion having a diameterslightly smaller than the diameter of said circular 9 waveguide so thatsaid dielectric means may be slidably inserted into Isaid circularwaveguide;

(g) said dielectric means being rotatable within said circular waveguideand having a rst position in which the dominant mode TEM linearlypolarized energy is propagated in said circular waveguide, saiddielectric means when rotated `clockwise from said irst position to asecond position, causes said dominant mode TEM linearly polarized energyto be transformed into dominant mode TEH left-hand circularly polarizedenergy; and when rotated counter-clockwise from said rst position to athird position, causes said dominant mode TEU linearly polarized energyto be transformed into dominant mode TEM right-hand circularly polarizedenergy, said dielectric means when `rotated to :any position other thansaid first, second and third position achieves a variable degree andsense of transformation of said dominant mode TEM linearly polarizedenergy to dominant mode TEU elliptically polarized energy;

(h) said dielectric means being axially adjustable with respect to saidcircular waveguide for varying the impedance of said device;

(i) said circular waveguide having a physical diameter of a value suchthat said circular waveguide will not propagate wave energy when saiddielectric means is not in position within said circular waveguide sothat d :Z1-JI? where d1 equals the physical diameter of said circularwaveguide when said dielectric means is in position, d equals thediameter of a circular waveguide which would propagate the dominant modeTEU of said energy when said dielectric means is not in position, and Kequals the dielectric constant of said dielectric means.

6. A polarizing device in accordance with claim wherein said dielectricmeans further includes a dielectric rod antenna connected to said headportion on the side remote from said body portion for radiating andreceiving polarized energy into and from free space, respectively.

7. A polarizing device in accordance with claim 6 wherein the other endof said circular waveguide has a peripheral U-shaped flange portionwhich serves as a quarter wave choke for reducing side lobes of theradiation pattern of the dominant mode TEM polarized energy radiatedfrorn said rod antenna, said rod antenna extending away from said otherend of sai-d circular waveguide and lying substantially outside of theplane of said other end of said circular waveguide.

8. A polarizing device in accordance with claim 5 wherein saiddielectric means further includes a coneshaped portion connected to saidhead portion on the side remote from said body portion, said cone-shapedportion extending away from said body portion and positioned within saidcircular waveguide.

9. A polarizing device for transforming dominant mode TEM, linearly-polarized energy into dominant mode TEM elliptically polarized energy,said device comprising:

(l) a rectangular waveguide having two ends;

(2) a circular waveguide having two ends;

(3) a tapered waveguide transition section connecting one end of saidrectangular waveguide to one end of said circular waveguide fortransforming said dominant mode TEM, linearly polarized energy intodominant mode TEU linearly polarized energy;

(4) an elongated dielectric polarizer having a wedge shaped bodyportion, a cylindrical head portion and and a cylindrical neck portionconnecting said body portion to said head portion;

(5) a dielectric rod antenna in the form of a frustum of a coneconnected to said head of said polarizer on the side remote from saidneck portion for radiating and receiving polarized energy into and fromfree space, respectively;

(6) a quarter-wave choke in the form of a U-shaped peripheral flangeconnected to and encompassing said other end of said circular waveguidefor reducing side lobes of the radiation pattern of the dominant modeTEM polarized energy radiated by said rod antenna into free space; and

(7) means for adjustably holding said polarizer in a predeterminedposition within said circular waveguide;

said polarizer being adapted to be slidably inserted into said circularwaveguide with said body portion extending at least partially into saidtransition section, said polarizer being rotatably adjustable withinsaid circular waveguide for providing a variable degree and sense oftransformation of said dominant mode TEM linearly polarized energy todominant mode TEM elliptically polarized energy, said polarizer beingaxially adjustable with respect to said circular waveguide for varyingthe impedance of said device, said circular waveguide having a diametersuch that said circular waveguide will not propagate said dominant modepolarized energies when said polarizer is not in position within saidcircular waveguide so that d 1 wherein d1 equals the physical diameterof said circular waveguide when said polarizer is in position, d equalsthe physical diameter of a circular waveguide which would propagate saiddominant mode TEU polarized energies when polarizer is not in positionand K equals the dielectric constant of said polarizer, sai-d rodantenna extending away from said other end of said circular waveguideand lying substantially outside of the plane of said other end of saidcircular waveguide.

10. A polarizing device for transforming dominant mode TEM, linearlypolarized energy into dominant mode TEu elliptically polarized energy,said device comprising:

(l) a rectangular waveguide having two ends;

(2) a circular waveguide having two end-s;

(3) a tapered waveguide transition section connecting one end of saidwaveguide for transforming dominant mode TEM, linearly polarized energyinto dominant mode TEM linearly polarized energy;

(4) an elongated dielectric polarizer having a Wedge shaped bodyportion, a cylindrical head portion connected to said body portion and acone shaped portion connected to said head portion on the side remote.from said body portion;

(5) means for adjustably holding said polarizer in a predeterminedposition within said circular waveguide;

said polarizer being adapted to be slidably inserted into said circularwaveguide with said body portion extended at least partially into saidtransition section and the remainder of said polarizer being positionedwithin said circular waveguide, said polarizer being rotatablyadjustable within said circular waveguide for providing a variabledegree and sense of transformation of said dominant mode TEM linearlypolarized energy to dominant mode TE11 elliptically polarized energy,said polarizer being .axially adjustable with respect to said circularwaveguide for varying the impedance of said device, said circularwaveguide having a diameter such that said circular waveguide will notpropagate said dominant mode polarized energies when said polarizer isnot in position within said circular waveguide so that wherein d1 equalsthe physical diameter of said circular waveguide when said polarizer isin position, d equals the physical diameter of a circular waveguidewhich would propagate said dominant mode TEM polarized energies whensaid polarizer is not in position, and K equals the 1 l l 2 dielectricconstant of said polarizer. electric means is not in position withinsaid circular 11. A device for transforming linearly polarized energywaveguide so that, to elliptically polarized energy, said devicecomprising: d

(a) a rectangular waveguide coupled to a circular waved1=-: guide by atapered waveguide transition section; and 5 W/K (b) adjustabledieieetfic means Positioned Within Said where d1 equals the physicaldiameter of said circular circular waveguide Sand extending into Saidtransition waveguide when said dielectric means is in position, dsection; equals the physical diameter of a circular waveguide which saiddielectric means being rotatable to a first position would propagate thedominant mode TEM of said energy in which said linearly polarized energyis transformed 10 when said dielectric means is not in position, and Kequals to elliptically polarized energy polarized in one anguthe`dielectric constant of the dielectric means. lar direction, androtatable to a second position in which said linearly polarized energyis transformed to References Cited by the Examiner ellipticallypolarized energy polarized in angular di- UNITED STATES PATENTS rectionopposite to said one angular direction, said 15 dielectric means alsobeing axially adjustable with reggg gigispect to said crrcular waveguidefor varying the 1m- 0161504 1/62 Alford et al. 33,3 21

pedance of said device, said transition section having a lengthapproximately two wavelengths long in free FOREIGN PATENTS space at thecenter frequency of said energy, and said 20 1 067 092 10/59 Germanycircular waveguide having a diameter approximately one-half wavelengthlong in free space at the center HERMAN KARL S A ALB ACH PrimaryExaminer frequency of said energy, wherein said circular waveguide willnot propagate wave energy when said di- ELI LIEBERMAN Examme".

5. A POLARIZING DEVICE COMPRISING, IN COMBINATION: (A) A RECTANGULARWAVEGUIDE; (B) A CIRCULAR WAVEGUIDE; (C) A TAPERED WAVEGUIDE TRANSITIONSECTION COUPLING ONE END OF SAID RECTANGULAR WAVEGUIDE TO ONE END OFSAID CIRCULAR WAVEGUIDE, SAID TRANSITION SECTION BEING APPROXIMATELY TWOWAVE LENGTHS LONG IN FREE SPACE AT THE CENTER FREQUENCY OF SAID ENERGY;(D) ELONGATED DIELECTRIC MEANS POSITIONED WITHIN SAID CIRCULAR WAVEGUIDEAND EXTENDING INTO SAID TRANSITION SECTION; AND (E) MEANS FOR ADJUSTABLYHOLDING SAID DIELECTRIC MEANS WITHIN SAID CIRCULAR WAVEGUIDE; (F) SAIDDIELECTRIC MEANS COMPRISING A WEDGE-SHAPED BODY PORTION CONNECTED TO ACYLINDRICAL HEAD PORTION, SAID BODY PORTION BEING APPROXIMATELY ONE-HALFWAVELENGTH LONG IN FREE SPACE AT THE CENTER FREQUENCY OF SAID ENERGY ANDSAID HEAD PORTION HAVING A DIAMETER SLIGHTLY SMALLER THAN THE DIAMETEROF SAID CIRCULAR WAVEGUIDE SO THAT SAID DIELECTRIC MEANS MAY BE SLIDABLYINSERTED INTO SAID CIRCULAR WAVEGUIDE; (G) SAID DIELECTRIC MEANS BEINGROTATABLE WITHIN SAID CIRCULAR WAVEGUIDE AND HAVING A FIRST POSITION INWHICH THE DOMINANT MODE TE11 LINEARLY POLARIZED ENERGY IS PROPAGATED INSAID CIRCULAR WAVEGUIDE, SAID DIELECTRIC MEANS WHEN ROTATED CLOCKWISEFROM SAID FIRST POSITION TO A SECOND POSITION, CAUSES SAID DOMINANT MODETE11 LINEARLY POLARIZED ENERGY TO BE TRANSFORMED INTO DOMINANT MODE TE11LEFT-HAND CIRCULARLY POLARIZED ENERGY; AND WHEN ROTATEDCOUNTER-CLOCKWISE FROM SAID FIRST POSITION TO A THIRD POSITION, CAUSESSAID DOMINANT MODE TE11 LINEARLY POLARIZED ENERGY TO BE TRANSFORMED INTODOMINANT MODE TE11 RIGHT-HAND CIRCULAR LY POLARIZED ENERGY, SAIDDIELECTRIC MEANS WHEN ROTATED TO ANY POSITION OTHER THAN SAID FIRST,SECOND AND THIRD POSITION ACHIEVES A VARIABLE DEGREE AND SENSE OFTRANSFORMATION OF SAID DOMINANT MODE TE11 LINEARLY POLARIZED ENERGY TODOMINANT MODE TE11 ELLIPTICALLY POLARIZED ENERGY; (H) SAID DIELECTRICMEANS BEING AXIALLY ADJUSTABLE WITH RESPECT TO SAID CIRCULAR WAVEGUIDEFOR VARYING THE IMPEDANCE OF SAID DEVICE; (I) SAID CIRCULAR WAVEGUIDEHAVING A PHYSICAL DIAMETER OF A VALUE SUCH THAT SAID CIRCULAR WAVEGUIDEWILL NOT PROPAGATE WAVE ENERGY WHEN SAID DIELECTRIC MEANS IS NOT INPOSITION WITHIN SAID CIRCULAR WAVEGUIDE SO THAT
 6. A POLARIZING DEVICEIN ACCORDANCE WITH CLAIM 5 WHEREIN SAID DIELECTRIC MEANS FURTHERINCLUDES A DIELECTRIC ROD ANTENNA CONNECTED TO SAID HEAD PORTION ON THESIDE REMOTE FROM SAID BODY PORTION FOR RADIATING AND RECEIVING POLARIZEDENERGY INTO AND FROM FREE SPACE, RESPECTIVELY.